Metals are a group of elements known for their distinct physical properties, which include malleability, ductility, shininess, and excellent conductivity of heat and electricity. They are typically solid under normal conditions, with the exception of mercury, which is a liquid at room temperature. Metals are generally extracted from ores found in the Earth's crust, and their ability to lose electrons makes them good conductors. The reactivity of different metals varies significantly; some, like gold and platinum, are noble and resistant to corrosion, while others, such as iron, oxidize or rust when exposed to moisture.
The use of metals has been pivotal in the development of civilizations. The discovery of copper and its alloys like bronze (BronzeAge) heralded a new era in tool and weapon making, which significantly altered the course of human history. The ability to manipulate metals gave rise to the Iron Age, which saw even stronger and more durable materials playing critical roles in the advancement of agricultural tools, warfare, and construction techniques. Today, advanced metals such as titanium and tungsten are crucial in high-tech industries, including aerospace and medicine, due to their strength and resistance to environmental challenges.
On the atomic level, metals are characterized by a structure known as metallic bonding, where electrons are not bound to individual atoms but instead form a cloud of electrons that float freely around the metal's positive ions. This "sea of electrons" is the reason behind their high conductivity and the capacity to reflect light, giving metals their characteristic luster. Metals can also form alloys, which are mixtures of two or more metallic elements, such as steel, an alloy of iron and a small amount of carbon, which is harder and more versatile than pure iron.
In modern technology, metals play indispensable roles. Rare metals like Gallium and Indium are critical in the production of semiconductors and liquid crystal displays respectively. Precious metals such as Rhodium and Palladium are essential in catalytic converters, which reduce harmful emissions in vehicles. The demand for these and other metals, like lithium and cobalt, has surged due to their applications in batteries, particularly for electric vehicles and renewable energy systems. This surge underscores the ongoing importance of metals in achieving technological advances and environmental sustainability.